I want to change the color of the feature article's title to red. My site is http://seenees.co.nf
I want the words "Sheila", "Ching", and "Daughter" to be in red. I tried to put this in the custom CSS but it's not working but I have zero knowledge in coding and just started on WordPress 2 days ago so I'm just trying to use my common sense based on what I've read.

.entry-title {
font-size: 0px;
font-color: red;
}

I don't want the page title to show up in the actual page (hence font size is zero) but I do want it to show on the Frontpage (which it is) but I want to change it's font colour.

A great intro to firebug is this video. It shows you how to inspect an element on your site and how to play with firebug realtime to see what things would look like if you made them permanent.

I also really like her CSS intro videos. Here's her first. You can see the others on her channel. She takes things at just the right pace for a complete beginner (which I was a month ago).

To remove the headings on the pages, you shouldn't set the font size to 0px, because this doesn't really do what you intend: it leaves all the vertical margins, padding etc. So yes, the text is invisible, but (in this case) it leaves a lot of vertical space hanging around that you don't need. Better would be to use:

.page .entry-title {
display: none;
}

That deletes the entry title on the pages. If you want to delete it from posts, use:

.post .entry-title {
display: none;
}

The CSS you need for your front page is:

.marketing h2 {
color: red;
font-weight: normal;
}

You can either put it in a child theme (which 2createawebsite also covers) or in the Custom CSS section of Customiz'it!

The .marketing singles out the specific fontpage featured titles, rather than all the h2s. So you should see the red only only on the front page.